


take a bite out of you

by yoonminoml (fanficloverme96)



Category: IDOLiSH7 (Video Game)
Genre: Cuckolding, M/M, Sibling Incest
Language: English
Status: Completed
Published: 2020-10-01
Updated: 2020-10-01
Packaged: 2021-03-07 22:15:47
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,562
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26745001
Author URL: https://archiveofourown.org/users/fanficloverme96/pseuds/yoonminoml
Summary: He knows the boy loves him. He knows that he owns Tenn’s heart in a lot of ways. Tenn tells him many times that he occupies his mind plenty of times.Gaku just doesn’t own all of Tenn’s heart, like he doesn’t occupy all of Tenn’s thoughts.
Relationships: Kujou Ten/Nanase Riku, Kujou Ten/Nanase Riku/Yaotome Gaku, Kujou Ten/Yaotome Gaku
Comments: 6
Kudos: 32





	take a bite out of you

**Author's Note:**

  * For [sparkleshootingstar](https://archiveofourown.org/users/sparkleshootingstar/gifts).



The thing about dating Tenn is that Gaku knows he’s never gonna be the boy’s first.

He knows the boy loves him. He knows that he owns Tenn’s heart in a lot of ways. Tenn tells him many times that he occupies his mind plenty of times.

Gaku just doesn’t own  _ all _ of Tenn’s heart, like he doesn’t occupy all of Tenn’s thoughts.

The second one is reasonable - he’s not looking to feed his ego by fooling himself that he’s all Tenn thinks about. He’s confident about himself but he’s not  _ that  _ egoistic. He’d be lying to himself if he says that Tenn is all he thinks about, because he really isn’t. He’s what Gaku thinks  _ most  _ of the time, sure, but Gaku could only  _ dream _ of a reality where he could afford to think about only Tenn. 

The first one, however -

Gaku loves Tenn. He loves him with everything he has and he would not be lying if he said he would be willing to take a bullet for this boy. His heart only belongs to Tenn and he loves Tenn so much that at the beginning of their relationship, or even before that, he said he would not mind if Tenn doesn’t feel the same way about his own heart. 

Gaku just doesn’t expect that Tenn would take it literally.

He still loves Tenn a lot, even if he has to sit on this chair, hands balled into fists on his lap as he watches the boy he loves kissing another boy passionately on the bed in front of him, fully aware that Gaku is watching and taking delight in it.

Even if the boy Tenn’s kissing is his own twin brother, Riku.

Tenn loves Gaku and tells him that he has a special spot for him in his heart. 

It’s just that Riku owns all of his heart, including that special spot for Gaku, and Gaku has to be willing to share as much as Riku is willing to have Gaku take a corner of what would otherwise belong exclusively to him. 

“Gaku,” Tenn purrs, giggling softly when his brother nuzzles along his jaw. His lips are wet with saliva and his eyes are filled with a slow burning lust, complementing the coy smile he has on his face. “Are you watching well? I’m giving you a good show, aren’t I?”

“Is Yaotome-san learning well?” Riku smirks, “Tenn-nii praised you a lot about your skills in bed that it makes me really curious.”

“Riku, would you like to see for yourself?”

“Oh? Are you asking me to watch Yaotome-san fuck you on these sheets?” Riku hums thoughtfully. “I’m not sure I’m in the mood for voyeur this time around.”

Tenn kisses the corner of Riku’s lips before hooking his arms around his brother’s neck. There is a cheeky glint in his eyes as he meets Gaku’s gaze before he turns his head, whispering into Riku’s ear. His lips barely brushes his brother’s earlobes as he murmurs out the words loud enough for Gaku to hear.

“I’m saying you should let  _ me _ watch Gaku fuck  _ you _ , instead.”

While the idea would have repulsed Gaku on a normal day - Riku’s attractive in his own right but Gaku isn’t attracted towards him that way -, maybe it’s the way Tenn says it, with that playful gaze and breathy whispery way of talking that the idea sends a shiver down Gaku’s spine and for a split second, he even  _ considers _ the idea.

He doesn’t voice this out, but Gaku has a bad habit of wearing his emotions on his sleeves. His real feelings might have shown on his face because Tenn giggles again before turning Riku on the lips, parting his brother’s lips to slip his tongue in. The twins’ kisses are often like this - wet and dirty, with tongues and teeths and lots of saliva wetting their lips and dripping down their chins.

Tenn gasps prettily into the kiss when Riku’s hand wraps around his cock and the sound goes straight to Gaku’s groin. He groans where he sits, shame pooling into his stomach just as the beginning of his arousal does. This sound doesn’t go unnoticed by Riku, who breaks off the kiss to smirk at Gaku. There is something challenging in the way Riku looks at him, though Gaku would be an idiot to think that he holds any sort of threat to this boy.

Riku treats him with just enough tolerance of an adult towards a misbehaving toddler, if anything, simply because Tenn treats Gaku with a lot of affection. He doesn’t hate Gaku per say, just as Gaku doesn’t hate him, but he does find amusement in reminding him who Tenn belongs to more - or who Tenn really belongs to completely.

Tenn loves Gaku. He really does.

Just not the same way Gaku loves him.

“Yaotome-san _ is  _ very attractive,” Riku agrees, “I might take you up on that offer some day. What do you think, Yaotome-san? Do you think I can warm your bed as well as Tenn-nii?” Before Gaku could answer, Riku licks the shell of Tenn’s ear as he starts stroking his brother’s cock, earning a squeak from him. “I know Tenn-nii is an excellent bed warmer. He just reacts so beautifully, doesn’t he? It almost makes me jealous knowing that you can have a taste of him.”

“Don’t be jealous, Riku - h-ah!” Tenn leans heavily against Riku, his breath coming out as pants as he endures Riku’s ministrations. “I’ll always be here if you’re feeling lonely. You know my body - hm~! - is yours, right? Gaku won’t mind. Right, Gaku?”

“I…” Gaku grits his teeth. “I only want to keep you happy, Tenn.”

“Mmph!” Tenn’s smile is coquettish. “You always make me happy, Gaku. I love you so much. That’s why I’m putting on a show for you.” He whines when Riku’s finger brushes over his slit. “Riku~ Help me put on a show for Gaku, okay? Make sure - hngh!” He buries his face at the crook of his brother’s neck, the pleasure rolling through him in waves. “Make sure Gaku is having a good time.”

Riku kisses the side of Tenn’s throat. “I think Yaotome-san is having an  _ excellent  _ time.”

Gaku’s hand is fumbling for his jeans buttons, already halfway undoing them when Riku coaxes Tenn onto his back. His fingers slip under the band of his boxers as he watches Riku hook Tenn’s legs over his shoulders, his arms braced at each of Tenn’s sides to cage him under his weight. Tenn’s hips lift slightly in this positon and Gaku could see Tenn’s cock, hard and flushed against his stomach, now smeared with the boy’s pre-cum.

He could also see Riku’s cock lining up against Tenn’s entrance, almost in awe at how much bigger it is compared to his own older twin brother’s. The size difference is obvious enough that the idea of Tenn taking it on probably a regular basis is enough to make Gaku’s throat go dry. 

The thing about Tenn is that he loves taking it deep. Gaku’s own cock is of a considerable size - big enough that Tenn couldn’t quite wrap his hands around it fully whenever he jerks Gaku off during their times together - and the memory of him begging for Gaku to fuck him deep and fast with it is fresh in Gaku’s memory. Or rather, it’s burned into the deep recesses of his mind that forgetting it is probably impossible at this point.

When Tenn lets out a high pitched moan when Riku pushes into him, his fingers clawing into the mattress as his back arches off of it, Gaku is reminded yet again of how  _ insatiable  _ Tenn is in bed.

And he has a sneaking suspicion as to why he is.

Whenever Gaku does it with Tenn, he typically starts off slow and gentle. Whether or not he maintains that afterwards is another thing entirely, but no matter how many times Tenn proves to him that he’s able to take Gaku no matter how rough he gets with him, Gaku prefers to take his time with Tenn - unravelling him bit by bit until Tenn’s reduced to a sobbing mess as he cries out Gaku’s name, his nails raking deliciously down his back.

Riku, on the other hand, quickly proves to prefer the exact opposite.

“Hya~!” Tenn squeals, “Riku~! H-hngh, y-you feel so big! So rough with me, Riku!”

“But that’s just how you like it, isn’t it?” Riku purrs, “Right, Yaotome-san?” he asks, meeting Gaku’s gaze, “Tenn-nii loves it when you thrust into him deep and rough with barely any preparation.”

He rocks into Tenn roughly as if to prove a point, and Tenn makes a sound that might have hinted discomfort - maybe even pain - but his hands grip Riku’s shoulders tightly and his legs fall from Riku’s shoulder to wrap around the boy’s waist to pull him closer. He throws his head back and from where Gaku sits, he could see how his eyes had rolled slightly back and his lips part, his tongue peeking out from between his teeth.

“Mm, Riku, more...more!” Tenn sobs, “Y-you feel so good!”

He shudders and sighs and straight up screams when Riku thrusts into him deep, tears rolling down his cheeks as his pleasure becomes more and more apparent. Gaku swallows, his hand fumbling for his own cock as he watches the boy he loves getting fucked silly by his own younger brother. 

He’s familiar with Tenn’s pleasured cries and the way he lets go of his inhibitions whenever he has sex with Gaku. He has all of the pretty sounds Tenn makes committed to his memory. 

But while Gaku draws them out gradually, letting Tenn’s pleasure build up like a crescendo along with his moans and cries, Riku tears them out of Tenn’s throat from the very beginning, giving him little to time to adjust and brace himself for the sensations - merely smirking in satisfaction as Tenn drowns in his own pleasure and begs for more. 

He understands why Tenn likes it rough. With someone like Riku to indulge him all the time, it’s really not hard to imagine why. 

“Does Yaotome-san fuck you like this, Tenn-nii?” Riku asks breathlessly, “Or is he sweet and romantic and takes his time undoing you like you’re a present to be savored?”   
  


Tenn giggles, his entire body rocked by the intensity of Riku’s thrusts. “Gaku is very gentle to me. He makes me feel so loved~!” He turns his head to look at Gaku, his lips curling when he sees what Gaku’s hand is doing. “Gaku, are you enjoying this? Am I entertaining you? It’s your reward, darling. You always make me feel so loved whenever we have sex. I feel like the luckiest man alive.”

“Don’t I make you feel loved, Tenn-nii?” Riku says with a mock hurt tone.

Tenn strokes Riku’s cheek. “You make me feel a lot of things, Riku. You make me feel _ yours _ .” He gasps, his fingers digging further into Riku’s skin when his brother picks up the pace of his thrust. “M-mm! So intense, Riku! H-ah!” Another breathless giggle. “A-are you jealous of Gaku? Y-you can’t be jealous, Riku. You  _ promised. _ ”

He says the last word in a sugary coy tone that sends more heat down Gaku’s groin. He groans, his hand moving up and down his hard cock, his eyes never leaving Tenn, whose body is sweaty and shaking from the force of Riku’s ministrations. The mattress creaks loudly, intermingling with the sounds of Tenn’s broken moans and the obscene wet snapping sounds of the twins’ hips meeting together. 

“Say out your boyfriend’s name for me, Tenn-nii,” Riku purrs, “Make him feel noticed. See? He’s touching himself so much. Probably imagining fucking you in my place.”

Gaku doesn’t even deny this. As he strokes himself faster and faster, he imagines holding Tenn’s body down and spreading his legs before pushing himself into Tenn’s tight wet heat. They’ve done it so many times before and yet, the addictive feeling of embracing Tenn never fades away. Instead, it grows over time.

“Gaku,” Tenn moans, “Hm… Gaku, Gaku…” His name is nothing but a slurred murmur on Tenn’s lips. “D-do you feel good, darling? I feel so good right now. I want you next time, okay? Just imagining it makes me -” His words are cut off by another high-pitched moan. “Gaku~! I-I want you so much! I feel so good, darling! S-see?” His legs are no longer wrapped around Riku’s hips, falling further apart as Riku fucks him roughly. His head lolls to the side, drool dripping down his tongue. “Hya~! I want more...Riku, Gaku~! Next time I want both of you, okay~?”

God, the idea alone is enough to nearly send Gaku right off the edge.

“Tenn, you…” Gaku grits out. He curls into himself, letting the pleasure drive him nearer and nearer to his climax.

“Greedy little thing aren’t you, Tenn-nii?” Riku chuckles, “What are we going to do with you?”

He changes the position, hooking one of Tenn’s legs on his shoulders before thrusting at a different angle. Tenn squeaks, burying his face into the mattress and grasping the sheets as he takes Riku’s thrusts. “R-Riku, I’m close! H-ah, I c-can’t h-hold on any longer -!”

Tenn climaxes with a broken cry, coating his stomach with white strips of his release. It doesn’t take long for Gaku to come as well, shuddering into his own touch, his body bent slightly forward as he catches his breath. 

Riku comes with a loud groan, his hips snapping against Tenn’s one last time before he jerks and shudders against him, Tenn’s name spilling from his lips. 

“Gaku, look~”

Gaku looks up at the call of his name. Tenn is half-lying on the mattress, his hands hooked under his legs to keep them spread apart as he exposes his hole for Gaku to see. Gaku could see the ring of muscle still twitching weakly, the skin around it coated with cum. Some of Riku’s release is still oozing out from Tenn’s hole. Tenn giggles as he hooks his pinkies at his hole to open it a little further.

“Riku let out so much… Gaku, did you enjoy the show?”

Gaku doesn’t notice Riku had walked up to him until Riku blows air against the side of his throat, chuckling in amusement when Gaku jerks in surprise.

He wraps his arms around Gaku’s shoulders from behind, nipping the shell of Gaku’s ear. 

“We still have all night, Yaotome-san,” Riku coos, “Why don’t we take up Tenn-nii’s offer?”

Gaku swallows, his mind spinning. “Which one?”

Riku chuckles just as Tenn lets out a smile, the light in his eyes bright and eager.

“Both,” they say simultaneously.

“I love you, Gaku,” Tenn says, after walking up to him and sitting on his lap. 

“I think I’m falling in love with you, Yaotome-san,” Riku whispers, “Make us feel good?”

Tenn flutters his lashes. “Gaku...play with us?”

Gaku inhales sharply. He has an answer in his mind, the words ready at the tip of his tongue.

He ends up never remembering what it is, because his lips are busy capturing Tenn’s lips into a feverish kiss while Riku embraces him from behind and mouths at his neck, his lips curling up into a smile.

“Play with us a little longer... _ Gaku _ .”

  
  
  


**Author's Note:**

> Happy Birthday, my dear heathen friend huehue


End file.
